1. Field of the invention
This invention relates to a robot apparatus of the type walking on two legs, which robot apparatus is capable of performing autonomous motions responsive to external stimuli or inner states, and a method of status expression by the robot apparatus.
This application claims the priority of the Japanese Patent Application No. 2003-028897 filed on Feb. 5, 2003, the entirety of which is incorporated by reference herein.
2. Description of Related Art
A mechanical apparatus for performing the motion simulating the movements of the human being, using the electrical or magnetic operations, is termed a “robot”. The robot started to be used extensively towards the end of the sixties. Most of the robots used were industrial robots, such as manipulators or transporting robots, aimed at automating or performing unmanned operations in plants.
Recently, developments of practical robots, supporting the human life as a partner of the human being, that is, supporting human activities in variable aspects of living environments or other situations in the human life, are under way. In distinction from the industrial robots, these practical robots have the ability to learn on their own the method of adapting themselves to individuals having different personalities in variable aspects of the human living environment or to variable environments. For example, a pet type robot, simulating the bodily mechanism or movements of quadruples, e.g. dogs or cats, or a humanoid robot, simulating the bodily mechanism or movements of animals erected and walking on feet, such as human beings, is already being put to practical utilization.
These robot apparatus are capable of performing various movements, with emphasis placed on entertainment properties, as compared to industrial robots, and hence are sometimes termed entertainment robot apparatus. Among these robot apparatus, there are those which act autonomously in dependency upon the information from outside or to the own inner states.
In the autonomous type robot apparatus, for example, the pet type robot apparatus, simulating the animals, such as dogs, the inner state expressing means, expressing the inner states, such as the emotional/feeling states, may be provided for smoothing the communication with the user.
Up to now, as these inner state expressing means, such a method has been used in which a light radiating device, effectively operating as an eye, is provided and turned on/off, or in which a square-shaped light radiating device is provided on the head part and is changed in color and luminance.
For example, the conventional robot apparatus, stated in the Patent Publication 1 (Japanese Laying-Open Patent Publication 2001-353674, is provided with light radiating means of a predetermined shape, effectively operating as an eye, for possibly expressing the feelings, such as ‘anger’ or ‘happiness’ responsive to the actions from the user, such as ‘patting’ or ‘stroking’, in order to transmit the feeling of the robot apparatus to the user by the turning on/off of the light radiating means.
If the robot apparatus is able to express the emotional state in this manner, the user is able to communicate smoothly with the pet type robot, while the user's affection and curiosity to the robot apparatus are correspondingly instigated to improve the entertainment characteristics of the robot apparatus further.
However, the conventional robot apparatus, stated in the above Patent Publication 1, needs to be provided with a different number of expression means in order to express a corresponding number of different emotional states or different perceptual recognition processing states. These expression means may be resources, including an actuator, first of all, in addition to the aforementioned light radiating means. However, in order to implement a robot apparatus requested to act autonomously in household environments, limitations are imposed on the physical weight and size, and hence on the expression means loaded on the robot apparatus, in favor of safety and portability. Thus, there is presented a problem that it is difficult to provide a number of the expression means equal to the number of the states owned by the robot apparatus.
On the other hand, if only expression means lesser in number than the contents of expression are usable, different expressions cannot be output except if the expressions of certain expression contents are interrupted. For example, the expressions of the emotional state need to be interrupted if the event of the voice heard (state of perceptual recognition processing) is to be displayed.
Moreover, as for the method for expressing the feeling, the emotional states are expressed solely by discrete color representations, for example, the color of the light represented by the light radiating device is green or orange for indicating ‘happiness’ or ‘anger’, respectively, such that it is not possible to make continuous representations of the inner state, such as how much the robot apparatus is ‘happy’, which is indispensable for enhancing the mutual understanding between the robot apparatus and the user.
In addition, as for the control method for the light radiating device, the routine practice is to specify the changes in color and luminance (pattern of light radiation) simultaneously to prepare a pattern file and to reproduce the pattern thus prepared at the outset to control the light radiation.
However, if the changes in color and luminance are specified simultaneously to prepare a pattern file, the changes in color and luminance need to be specified simultaneously. Should the expressions be made so that different meanings are imparted to the respective expression means in making the expressions, it is necessary to provide the number of files corresponding to the number of the combinations of the color and the luminance. Should the number of the combinations be larger, command management becomes more complex. Moreover, it is undesirable for the robot apparatus with limited resources to supervise the plural number of the commands.
On the other hand, the control command for the light radiating device is generally issued only when the output state has been changed. The routine practice is that, except if a new command is issued, the state which prevailed when the command has been issued last time is maintained.
However, if the light radiating device is controlled by a scheme in which the changes in color and luminance are specified simultaneously and in which the last state at the time point of end of the command is maintained, difficulties are met in processing an interrupt event during the time of steady status representations. That is, if an interrupt event, such as dancing performance, is carried out under a state steady status representations, such as representations of the emotional state, the turn-on state at the time point of completion of the dancing performance is maintained, except if the command for representing the emotional state is reissued at a time point of completion of the interrupt event.
For coping with this problem, it is necessary for the side issuing a command for representing the steady state to monitor the timing of the end of the interrupt event to re-issue the command. Moreover, in case the interrupt event processing is a command which should be executed in preference to the steady state representations, it is necessary for the command output of the steady state representations to monitor the state of the preferential command and to suppress the own command output.
An object which verifies the behavior is made up by behavior stating modules, each stating the behavior discretely autonomously, and outputs a command at an optional timing. Thus, when the command output control is to be made, the status of other modules needs to be monitored within the behavior stating modules. It is, however, highly inefficient to state the processing for the interrupt event in all of the modules to monitor the relationship among the modules.